Around 2 billion years ago, Oklo became a natural nuclear reactor beneath Africa, and its radioactive remains are still there

<iframe
  src="https://hindustansphere.com/embed/cluster/245d54c93ad11083cc8242e772e853610a844ca3"
  width="100%" height="320"
  style="border:0;max-width:680px"
  loading="lazy"
  title="Around 2 billion years ago, Oklo became a natural nuclear reactor beneath Africa, and its radioactive remains are still there"></iframe>